Screw shell light socket with gripping means



NOV. 18, 1 952 w GAST SCREW SHELL LIGHT SOCKET WITH GRIPPING MEANS Filed March 27, 1950 Patented Nov. 18, 1952 UNITED... PATENT OF F'I CE SCREW SHELL; LIGHT SQGKET-AWIFIP;

GRIPPING MEANS Adolph- Ws Gast, Evan ston, 111.:

Application March-27, 195i), Serial=No. 152,143 I ZQleims... (Cl. 173-3 8)- economical device. of the character described,

especially designed .to restrain thelamp base from becoming loosened. in the socket.

My invention is particularly-adapted-for use in miniature lamps-of the kinden rployed for lighting Christmas trees. r

A very common; diffic-ulty encountered in Christmas tree lights is the tendency for the lamps to comeloose in their sockets. This is particularly troublesome when the lamps are strung in series so that; theloosening of one lamp will extinguish the whole; string, makingit difiicult to determine which particular lampfhas become loose, or perhaps whether one'has burned out.

Commerciallamp socketsare usually made so that the lamp bases fit loosely therein and, in

order to hold the lamp against unscrewing, the

base must be screwed down tightly in thesocket to force the center terminal on the base firmly against the center contact in the socket. Nevertheless, thelamps often become loose when in use.

Another reason for frequent loosening of the lamps is the fact that the centralterminalsof lamp sockets and lamp bases are usually :rela;

tively flat, and one or both such terminals are usuallvmade of relatively soft metal of solder or the like, so that the engaged terminal surfaces present little resistance against tilting of the bulb in the socket.

A particular object of my invention is to provide a, simple form of spring-retaining means readily applicable to sockets of commercial form, for holding the bulb in place in the socket.

A further object of the invention is to provide. an improved form of center terminal, cooperating with the spring-retaining meanstfor holding thelamp bulb fromtilting and, therefore, loosening in its socket.

Other objects and advantages of the invention will appear from time to time as the following description proceeds.

The invention may best be understood by reference to the accompanying drawings, in which:

Figure 1 is a side view of a lamp and socket constructed in accordance with my invention, with the surrounding casing for the metallic part of the socket shown in dotted lines;

Figure 2 is an enlarged top plan view of the socket shown in Figure 1 with the lamp and its base removed;

2 Figure 3 is aside view of thesocket shown in Figure 2.;

Figure 4 is a detailedsection taken on line 1-4 of Figure 2;

Figure 5 is adetailed view showing thespringretaining member used with the socket shown in the foregoing figures.

Referring now to detailsof the embodiment of my invention illustrated in the drawing, anelectric light bulb ll], hereinshown in tapered formof the kind employed-withChristmas tree lights, includes a glass bulb H and :metallic base l2 threaded in the conventional manner for reception in athreaded metallic shell or socket l3, which may be surrounded as usual by an insulated lamp base, indicated in dotted linesat It in Figure 1. The metallic shell 13 includes a generally cylindrical body portion l6 flared at one end as indicated at I! and closed at the other end by a disc ll! of suitable insulating material having a centrally disposed metallic terminal l9 extendingtherethrough for engagement'with a central terminal (not shown) projectingas usual from the lower end of the lamp base I2. The side wall of body portion I6 is formed with a-rolled thread 20 so as to present opposed-threaded surfaces surrounding both the interior and exterior of said body portion intermediate its ends. In the form shown, the lower endof the body portion [6 is slightly tapered at 2l-and terminates in an annular bead2-2 withinwhich the edges of themsulating disc 48 are secured; The socket cone struction-so far described; is substantially. the same as is now commonly employed with commercial lampsockets, wherein 'the, cylindrical body portion [8 is formed by machinery, from a single piece of metal.

Referring now to the novel features'of my invention, Iprovide a substantially C-shapedspring clip, indicated at 25, preferably made of spring wire, having an approximately semi-circular portion 26 formedv to fit in the exterior thread of the body I6 and having inwardly arched gripping portions 21, 21 at the opposite ends thereof, continuous with the semi-circular portion 26. Two elongated slots 28 and 29 are cut through the side wall of the body portion [6 at the base of the thread 26 adjacent the lower end thereof, said slots being disposed to permit the arcuate gripping portions 21, 2'! of spring clip 25 to project into the interior of the cylindrical body I6 beyond the inner faces of the threads 20 but in alignment with said thread. As will be seen in Figure 2, the slots 28 and 29 are both disposed toward one side of the socket so that, when the spring clip is seated in the thread around the body IS, the inwardly arched gripping portions 21, 21 extend slightly more than one-half the distance around the body but with their out-turned terminal ends 21a spaced circumferentially from each other a substantial distance to facilitate the application of the spring clip to the body portion without distorting said clip.

The spring clip 25 is norm-ally placed under sufficient clamping tension to be held securely in place when the arcuate friction portions 21,

,2! are sprung into engagement in their respective slots 28 and 29 in the body l6, but inward movement of said friction surfaces is limited by engagement of the spring with the ends of said slots. The ends 27a of the spring clip are spaced apart slightly less than the diameter of the body l6, so as to permit the clip to be assembled in place on the latter by moderate radial pressure.

I also provide the center terminal 19 of the socket with an upwardly projecting contact point 39 disposed substantially on the longitudinal axis of the socket, as shown in Figure 4. This contact point is preferably made of relatively hard metal, such as brass or bronze, so that it will penetrate the comparatively soft solder-like metal commonly employed on the central terminals of commercial lamp bases.

The socket I3 is provided as usual with wire connections, herein consisting of one wire conductor soldered to the exterior of the tapered portion 2| of the body l6, and a second wire conductor 36 having a terminal portion soldered Within the hollow recess 3| on the exterior of the central metallic terminal [9. The conductors extend through a suitable aperture in the insulated base [4.

The use and operation of the device above described is as follows:

The spring clip 25 is applied to the exterior of the "shell body It with the arcuate gripping portions 21 of said clip extending through the slots 28 and 29 near the base of the thread under sufficient tension to permit a lamp to be screwed into, or unscrewed from, the socket in the usual manner without excessive torsional effort and without any damage to the threads of the lamp base.

The tension of the gripping members 27, 21 will be exerted on the exterior threaded portion of the lamp base. The arrangement is such that the lamp base will tend to be urged toward the side opposite the two friction members 27, 21 so that the lamp base will be securely held in the socket by friction at three widely-spaced points circumferentially thereof. Accordingly, my invention is adapted for use with lamp bases of conventional or standard threaded form, Without any special detents, or other locking members. As the lamp is screwed into the socket, the point 39 on the central terminal 19 of the socket will become partially imbedded in the relatively soft metal in the central terminal of the lamp base.

The lamp base will thus be restrained against .tilting in the socket with much greater effectiveness than in present commercial forms of lamp sockets, where the sockets are merely formed with a relatively smooth, button-like central terminal.

Although I have shown and described certain embodiments of my invention, it will be understood that I do not wish to be limited to the exact construction shown and described, but that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. In a screw socket for electric light bulbs, a shell of generally cylindrical shape open at one end and closed by a contact terminal at the other end, the side wall of said shell being interiorly and exteriorly threaded intermediate its ends, said side wall having two circumferentially spaced apertures along the base of its exterior thread at widely spaced angles to each other, and a substantially C-sh-aped spring clip extending in an arc of substantially more than and arranged to fit under clamping tension in said exterior thread, said spring having inwardly arched portions near its ends extending inwardly and then outwardly through the apertures in said shell for frictional engagement with the threads of a lamp base when screwed therein.

2. In a screw socket for electric light bulbs, a shell of generally cylindrical shape open at one end and closed by a contact terminal at the other end, the side wall of said shell being interiorly and exteriorly threaded intermediate its ends, said side wall having two circumferentially spaced apertures along the base of its exterior thread at widely spaced angles to each other, and a substantially c-shaped spring clip extending in an arc of substantially more than 180 and arranged to fit under clamping tension in said exterior thread, said spring having inwardly arched portions near its ends extending inwardly and then outwardly through the apertures in said shell for frictional engagement with the threads of a lamp base when screwed therein, and the free ends of said spring clip being spaced apart slightly less than the diameter of said shell to permit said spring clip to be pressed radially into place on said shell.

ADOLPI-I W. GAST.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 994,854 Mackin June 12, 19 1 1,160,435 Morey Nov. 16, 1915 1,167,473 Benjamin Jan. 11, 1916 2,385,478 Steinmayer Sept. 25, 1945 2,477,895 Pollock Aug. 2, 1949 

